The present invention relates to vehicles of the type that include an internal combustion engine, a cranking motor, and a battery normally used to power the cranking motor. In particular, this invention relates to improvements to such systems that increase of the reliability of engine starting.
A problem presently exists with vehicles such as heavy-duty trucks. Drivers may on occasion run auxiliary loads excessively when the truck engine is not running. It is not unusual for heavy-duty trucks to include televisions and other appliances, and these appliances are often used when the truck is parked with the engine off. Excessive use of such appliances can drain the vehicle batteries to the extent that it is no longer possible to start the truck engine.
Various systems have been developed that use a capacitor to supplement the vehicle batteries such that the vehicle can be started. Often, however, the capacitor is not completely isolated, and can lose its charge over time, for example by leaking through one or more diodes. In other systems, wherein the capacitor is completely isolated when not in use, the capacitor is also isolated from the one or more switches or relays used to connect the capacitor to the cranking motor, such that the capacitor cannot be used to close the switch or relay to bring the capacitor on line.